2000 freightliner Century with 1.400,000 miles

try to find maintanance/repare history. bearings are usually worn at this milage, but I drop oil pan at 650 K( ex shnider truck) and found all new bearings but old oil pan gasket, that leaks

 

I would have the CAC checked and have the test plug put in the right side, that way you can test the valve guides, intake manifold, and air compressor. A bearing roll in is cheap to do, and a good thing to do. If everything is cleaned up you can reuse the gasket.
I hear a lot of talk about bull gear problems, I have had more problems with 3406B's bull gears than the one Detroit. He hit a train, and cracked a tooth.
Every other bull gear problem was a head change and they did not set the gear lash properly.
When you change the oil it will not use any, you want to monitor it every day when it starts using oil, you want to change the oil at least before double that mileage.
I live in B.C. and we had many S60's get above 1.6 million miles and we have mountains and these trucks were hauling 144,000 lbs over two mountains.

 

CAC is the big air cooler looks like a radiator which has hoses going from your turbo to your intake. They tend to get small holes which keep the turbo from sending enough air pressure to the intake. Down just a couple pounds will dramatically cut fuel economy and power. Literally holes smaller than the eye can see. Also the boots connecting the CAC leak after couple hundred thousand miles.

 

Charge Air Cooler.
When you do the bearings check the oil pump if worn replace it. The oil pressure regulators, I always replace the springs, the oil pan gasket, wipe the block with Var-sol and when still wet, put silicone on all the block section lines.
Before you remove the oil pan add a gallon of ATF dextron 3 about a half hour before you drain the oil when the engine is hot, and keep it running above 1300 RPM, while you wash it will do or 20 miles before you bring it into the shop works the best. You will be amazed at how it will clean it. First remove the drain plug. I remove the oil pressure gauge hose and put in an adapter, and add air pressure, regulating it between 30 lbs and full pressure. Then punch a small hole in the filters and blow out the oil from them. I try and do this, and the draining the night before. Then in the morning give it one more blow down at full shop air pressure. While you remove the oil pan bolts, If the tentioners are worn replace them. If you remove the valve covers you can manually activate the solenoids for the Jake's and blow them out also.
That way it is not only clean, but a minimum of drips. Comes from years of experiance.

 

Will the C-10 have a CAC also? I presume this is what's called an intercooler in other applications, right? What's involved in checking it, pressure test? Who can do it, dealer only or most shops? Also, what should I expect to spend for the test and can the CAC be repaired, or is it an R&R only? Any idea of cost for a new one (ballpark is fine)? Many thanks!